[clang] [Clang] __has_builtin should return false for aux triple builtins (PR #121839)

[Aiden Grossman via cfe-commits]

https://github.com/boomanaiden154 approved this pull request.

Changes to `__cpuidex_conflict.c` LGTM. I will put that on my TODO list.

https://github.com/llvm/llvm-project/pull/121839